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Liability, community, and just conduct in war

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Those of us who are not pacifists face an obvious challenge. Common-sense morality contains a stringent constraint on intentional killing, yet war involves homicide on a grand scale. If wars are to be morally justified, it needs be shown how this conflict can be reconciled. A major fault line running throughout the contemporary just war literature divides two approaches to attempting this reconciliation. On a ‘reductivist’ view, defended most prominently by Jeff McMahan, the conflict is largely illusory, since such killing can be justified by aggregating individuals’ ordinary permissions to use force in self- and other-defence. In opposition, a rival ‘nonreductivist’ approach holds that these considerations are insufficient for the task. One prominent version of non-reductivism grounds the permission to kill in combatants’ membership in certain kinds of group or association. The key claim is that participation in certain morally important relationships can provide an independent source of permission for killing in war. This paper argues that non-reductivism should be rejected. It does so by pushing a dilemma onto non-reductivists: if they are successful in showing that the relevant relationships can generate permissions to kill in war, they must also jettison the most intuitive restrictions on conduct in war—the constraint on intentionally killing morally innocent non-combatants most saliently. Since this conclusion is unacceptable, non-reductivism should be rejected.

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  1. McMahan (2009). For other booklength treatments of war from a reductivist perspective, see Fabre (2012) and Frowe (2014).

  2. This characterisation of reductivism is indebted to the helpful discussion in Lazar (2014).

  3. For an early statement of the Continuity Thesis, see Glover (1977: 251–252).

  4. The key debate among theorists of self-defence concerns the correct rendering of the ‘relevantly implicated’ clause for grounding liability For a representative sample, see Thomson (1991), Ferzan (2005), McMahan (2005), Quong (2012) and Tadros (2012).

  5. For a very useful collection of essays on this topic, see Rodin and Shue (2008).

  6. For the most sustained argument for this conclusion, see McMahan (2009: Chs. 1 and 2).

  7. On this point, see McMahan (2008).

  8. Though for a minority position which endorses both reductivism and the equality of combatants, see Steinhoff (2008).

  9. It should be noted that the dust is yet to settle on this objection. One line of resistance attempts to deny the dilemma directly, by arguing there are in fact morally relevant asymmetries between combatants and non-combatants in terms of the factors that ground liability (McMahan 2009: Ch. 5; McMahan 2011; Fabre 2009). For criticism, see Frowe (2014: Ch. 6). A different response aims to show that revising the relevant conception of liability can enable reductivists to draw the desired distinction between combatants and non-combatants (Bazargan 2013). A more radical view accepts the existence of the dilemma, but denies that the correct resolution requires rejecting reductivism. On this view, the correct conclusion is simply that many non-combatants on the unjust side of a war are liable to defensive killing. The dilemma does not reveal that reductivism is false, but that the principle of non-combatant immunity is (Frowe 2014: Chs. 6–8).

  10. For support for this claim, see the references contained in Parry (2015).

  11. For examples, see Fletcher (2002), Kutz (2005), Lazar (2012, 2013), Meisels (2012), Sparrow (2005) and Zohar (1993).

  12. On this point, see Lichtenberg (2008).

  13. Lazar supports his view with an argument from transitivity (Lazar 2013: 19–30).

  14. I borrow the terms ‘target-centred’ and ‘agent-centred’ from McMahan (1994: 268), who employs them to distinguish different conceptions of the justification of self-defence.

  15. McMahan briefly raises the possibility of an objection of this sort, but does not pursue it at any length (McMahan 2007b: 313). He also suggests an analogous line of objection to agent-centred accounts of self-defence (McMahan 1994: 270–271).

  16. Thanks to Jeff McMahan for suggesting this line of response.

  17. A related contingency problem for proposal is that it does not seem to apply to belligerent parties who are not a professional military, such as a disorganised militia or levee en masse.

  18. On this point more generally, see Simmons (1996).

  19. Thanks to Daniel Viehoff for this example.

  20. For detailed discussion, see Tadros (2011: Ch. 6).

  21. Jonathan Quong employs an analogous argument in order to constrain his agent-centred account of permissible self-defensive killing (Quong 2009).

  22. This is a particular problem for non-reductivists such as Lazar, who argue that reductivism renders too many non-combatants liable because non-combatants contribute to threats to the same degree as many combatants. If this is true, the intentional killing of many non-liable non-combatants will function eliminatively, by preventing them from contributing to threats. If this is false, then reductivists may not face the dilemma that Lazar claims that they do.

  23. The assumptions are generous in two respects: (1) There is a large difference in liability probabilities between the groups, while (2) keeping the proportion of combatants who are non-liable sufficiently high to support Lazar’s objections to reductivism.

  24. For versions of this view, see Lazar (2013: 40–41), May (2007: 67–117), Meisels (2012), Shue (1978).

  25. As mentioned above, the appeal to vulnerability may help substantiate the argument-from-cowardice discussed above. The thought being that the constraint on acts of killing that manifest cowardice is explained in terms of the constraint on attacking the vulnerable. Vulnerability may also provide a way of rehabilitating the Walzerian thought that the permission to target combatants is grounded in the fact that combatants pose threats, since presumably the ability to pose a threat negates an individual’s vulnerability, even if does not vitiate their right not be killed.


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For written comments on drafts of this paper, I am extremely grateful to James Lenman, Jeff McMahan, Seth Lazar, Helen Frowe, Ian Fishback, Michael Neu, Jonathan Quong, and especially Daniel Viehoff, Versions of this paper were presented at the Brave New World graduate conference at the University of Manchester in 2012, the Society for Applied Philosophy Annual Conference in 2012, and two seminars at the University of Sheffield. My thanks to the audience members at those events for helpful discussions, and to Saba Bazargan for commenting on the paper at the SAP conference. Work on this paper was supported by the Arts and Humanities Research Council, UK and the Society for Applied Philosophy, for which I am very grateful.

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Parry, J. Liability, community, and just conduct in war. Philos Stud 172, 3313–3333 (2015).

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